Colbert played clips of Rubio's speech during which Rubio wiped away sweat from his face, all leading up to the water-bottle reach.

"Don't worry, Sen. Rubio," Colbert said. "No one noticed — that you gave a speech."

But Colbert appreciated how tough it was to talk to millions of people. He found himself rather parched during the segment and needing some water. No worries: The secret to keeping the audience with you, he said, is to keep eye contact with the camera.

Colbert climbed over his desk, crawled on the floor and finally found a water bottle, keeping eye contact with the camera all the way through.

"You may have not noticed that I got a little thirsty there," Colbert said. "But that's how pros like me and Marco Rubio do it."